Method and apparatus for handling oil field emulsions



April 9, 1946. R. c. BUCHAN METHOD AND APPARATUS FOR HANDLING OIL FIELD EMULSIONS Filed Sept. 21, 1940 4 Sheets-Sheet l IN VENT OR.

ATTORNEY.

April 9, 1946. R. c. BUCHAN METHOD AND APPARATUS FOR HANDLING OIL FIELD EMULSIONS Filed Sept. 21, 1940 4 Sheets-Sheet 2 INVENT OR.

ATTORNEY.

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ATTORNEY.

April 9, 1946. R. c. BUcHAN METHOD AND APPARATUS FOR HANDLING OIL FIELD EMULSIONS Filed Sept. 21, 1940 4 Sheets-Sheet 4 ATTORNEY ?atented Apr. 9, 1946 METHOD AND APPARATUS FOR HANDLING OIL FIELD EMULSIONS Rudolph C. Buchan, Houston, Tex., assignor to Standard Oil Develop ration Delaware ment Company, a corpo- Application September 21, 1940, Serial No. 357,738 10 Claims. (01. 183-231) The present invention is directed to a method and apparatus for handling oil field emulsions.

In practically all cases salt water is produced concurrently with oil. The mixture, in its passage from the subsurface to the surface, becomes emulsified and the resulting emulsion must be resolved at the surface before the oil can be charged into the pipe lines. In the past, the customary practice has been to charge the mixture into a separating vessel, such as a gun barrel, either with preliminary heating or addition of emulsifying agents or with heating and/or the addition of emulsifying agent in the gun barrel.

The difiiculty has been encountered that, in addition to water, the oil contains gas which must be separated. This separation ordinarily takes place in the gun barrel. The expelling of the gas from solution, however, agitates the mixture and thereby renders separation of the water as a separate layer difilcu The principal object of the present invention is the provision of a method for handling such emulsions whereby agitation of the mixture by gas during the settling period is avoided.

An additional object of the present invention is the provision of an apparatus through which the mixture may flow by gravity through a plurality of stages including a heating stage and a settling stage and in which the mixture during each stage is in indirect heat exchange relation with the mixture during adjacent stages.

Further objects and advantages of the present invention will appear from the-following detailed description of the accompanying drawings in which Fig. l is a plan view of an apparatus suitable for the practice of the present invention;

Fig. 2 is a similar view with the roof removed;

Pg. 3 is a front elevation with a portion of the side wall removed;

Fig. 4 is an elevation of the right side of Fig. 1 with a portion of the wall removed;

Fig. 5 is a rear elevation of Fig. 1 with a portion of the wall removed;

Fig. 6 is a vertical section along the axis D-D of Fig. 1; and

Fig. 7 is a view of the entire assembly divided in half along a vertical plane passing through the longitudinal axis of the heater to show the interior arrangement of parts.

Referring to the drawings in detail, numeral I designates a tower having a, cover 2 with an outlet pipe 3 for the withdrawal of gas from the system. The interior of the tower I is divided into compartments A,

Compartment A is defined by a partition 4 extending from the bottom of the tower almost to the top of it, being welded to the side and the.

bottom of the tower, and by a partition 5 which is also welded to the bottom and the side of the tower as well as to partition 4, but which is of a lesser height than partition 4. Compartment A is provided with a fluid inlet 6 which may be arranged at a point intermediate the top of partition 4 and the top of partition 5.

Partition 5 constitutes one wall of compartment B. The other wall or compartment B is an extension of partition 4 with the bottom thereof cut away so as to provide an outlet for fluid. In other words, partition 4 is in the form of a chord having both of its side edges welded to the wall of vessel I. The lower end of partition 4 in compartment B is bent upwardly from the door of vessel I away from the compartment B and extends into a heating zone 'I in which is arranged a heater 8, said heater being removably mounted in the wall of vessel I and being provided with a gas inlet 9 and an outlet ill to a stack. The lower bent end II of partition 4 has a serrated edge I2 which serves to spread the fluid entering the heating chamber. The heating chamber is defined by the partition 4 and by a similar "partition I3 diametrically opposite to partition 4, a horizontal plate I4 welded to partitions 4 and I3 and to the wall of vessel I, and a vertical plate I5 welded to the rear end of plate I4 and the bottom of vessel I.

The partition I3 is similar in height to partition 4 and constitutes one wall of compartments C and D, these compartments being separated by a partition I6 which extends from the floor to a point below the top of partition I3 and also below the top of partition 5. The lower end of partition I3 in compartment C is cut away to permit the fluid to pass through the heating zone I upwardly through compartment C where it overflows into compartment D. The ,lower end of partition I3 in compartment D is cut away so as to permit fluid to pass beneath it into compartment E, which is defined by partition 4, partition 5, vertical plate I5, horizontal plate I4 and the wall of the vessel I. Compartment E is provided with an outlet Il at a level below the top of partition I5 and with a water outlet I8 at its bottom. There is also provided in the wall of vessel I, defining compartment E, a manhole I9. The removal of heater 8 provides a manhole for the rest of the vessel.

In operation, a mixture of oil and water con- B, C, D and E by partitions. taining gas is fed'into the vessel through entering pipe 6 and flows downwardly in compartment A, fllling the same until it overflows over the top of partition 5 and passes into compartment 13 through the heating zone I, upwardly in compartment C and downwardly in compartment D and upwardly in compartment E until the liquid in the vessel reaches an operating level which, in one part of the vessel, is the top of partition 5 and in the other part the vessel is the top of partition Hi. It will be noted that at this point there is a head of liquid in comaprtment A which causes the flow of liquid upwardly through compartment C and likewise there is a head determined by the difierence between the top of partition l6 and the outlet H for causing the oil to flow upwardly in compartment E,

With the liquid levels so fixed, the fresh feed is continually introduced through inlet pipe 6, causing a continuous overflow over the top of partition 5. Considerable water settles out in compartment A and ma be withdrawn through an outlet 20 at the bottom thereof. At this point of overflow over the top of partition 5 a major portion of the gas contained in the mixture is freed in a relatively cold state with respect to the gas freed subsequently from the mixture. This is an important feature of the process since if all the gas is expelled by heat it carries with it a considerable amount of the light ends of the oil. The objective in a process of this type is to separate the gas from the oil with a minimum separation of liquid constituents from the oil. Thispreliminary low temperature separation before the heating results in the recovery of a larger volume of higher gravity oil than is possible when the entire mixture is subject to heating from the outset.

The liquid passing out beneath the bottom of partition 4 in compartment B passes around the heater, which is regulated to maintain the temperature in this chamber at a temperature predetermined as suitable for the breaking oi. the emulsion, which will usually be somewhere in the neighborhood of 100 to 150 F. The liquid passing the heater moves upwardly in compartment C. The gas is disengaged from the oil by the action of heat and passes upwardly through compartment C with the fluid and is separated from the liquid when the latter passes over the top of partition l6. At the point of overflow of the fluid over the top of partition l8 it will be observed that the liquid head of the fluid isreduced substantially to zero. This separated 88s is bled off through outlet 3 at the top of the tower.

The mixed fluid passes downwardly through compartment D into compartment E where it is in a substantially quiescent state so that the water separates readily. There being no evolution of gas during this settling stage, the difliculty which has previously been encountered with the conventional treating apparatus is avoided. As will be observed, the fluid in compartment C is in heat exchange relation with the fluid in compartment 1), and the latter is in heat exchange relation with the fluid in compartment E, and in each case the fluid is in heat exchange relation with the heating chamber 1. Thus, there is a more or less uniform temperature maintained throughout the system beyond the heating zone and a very eflicient utilization of the heat is effected.

It will be apparent that many changes may be made in the apparatus and procedure described above without departing from the scope of the present invention. While the various zones in the embodiments shown may be arranged in a will-be apparent thatfthe individual-stages oi the method may be conducted in individual vesels. The apparatus may be made'in any desired proportions, flow is desired, to keep the top of partition 5 higher than the top of partition l8 which, in turn, must be higher than the outlet H.

The nature and objects of the present invention having been thus described and illustrated. what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. The method of treating a gas-containing, oil-water emulsion which comprises settling and drawing off free water from the mixture, cascading the remaining cold emulsion into a first pool to liberate gas, withdrawing emulsion from the lower portion of said pool into an upwardly flowing stream and simultaneously supplying heat to it, cascading the liquid into a second pool to liberate further gaseous constituents, withdrawing liquid from the lower portion of said second pool into a relatively quiescent settling zone and there stratifying the oil and water, separately withdrawing oil and water from said zone, and maintaining a blanket of evolved gases and vapors over the liquid at the same pressure throughout all of the steps of the method.

2. A method for resolving an oil and water emulsion containing gas which comprises flowing said mixture in a thin layer exposed to a free vapor space to release cold gas therefrom, passing the mixture through a heater, again flowing said mixture in a thin layer exposed to the aforesaid free vapor space to release hot gas therefrom, maintaining a substantially quiescent body of liquid having an oil layer and a water layer and an upper oil drawoff point and a lower water drawofl point, introducing the mixture, after release of hot gas, into a vertically intermediate point in said body of liquid above the water drawofl' point and withdrawing oil and water separately from said respective layers.

3. An emulsion treating apparatus comprising 45 a closed, upright tank, partitions in the tank terminating short of its top, and dividing it into a free water separating chamber having a first weir at its top, a passage extending downwardly from said weir, a laterally extending heating chamber, an upwardly extending passage having a second weir at its top at a level below said first weir, a passage extending downwardly from said second weir, and a relatively quiescent settling chamber, a mixture inlet and a first water outlet for said free water separating chamber,

a heater in said heating chamber, a second water,

outlet from said settling chamber and an oil outlet from that chamber at a point above said second water outlet but below the level of said a second weir, and a gas outlet from the tank above the level of said first weir.

4. An emulsion treating apparatus comprising a closed upright tank, first and second upstanding partitions extending from the bottom, terminating short of the top, and dividing the tank into intermediate and first and second outer compartments, respectively, a partition extending from the bottom of the first outer compartment and terminating short of the top of said upstanding partitions to form a first weir and dividing said first outer compartment into a free water settling chamber and a first downflow passage, a. partition extending from the bottom of the second outer compartment and terminating short single vessel by the utilization of partitionsgit it being necessary only, when gravity of the level of the first weir to form a second weir and dividing the second outer compartment into an upfiow passage and a second downfiow passage, aligned openings in the lower portions of said upstanding partitions from said first downflow passage and to said upfiow passage, respectively, walls forming a heating chamber closed to said intermediate compartment and connecting said openings, a heater in said heating chamber, an opening in the lower portion of said second upstanding partition connecting said second downflow passage and said intermediate compartment, an emulsion inlet to said free Water settling chamber, a first water outlet from the lower portion of said free Water settling chamber, a second water outlet from the lower portion of said intermediate compartment, an oil outlet from said intermediate compartment above said second water outlet but below the level of said second weir, and a gas outlet from the tank above the level of the first weir.

5. A method for handling an oil and water emulsion containing gas comprising establishing at least three bodies of liquid having diflerent liquid levels and a common vapor space, the level of the first body being higher than that of the second body, and the level of the second body being higher than that of the third body, the first and second bodies being in liquid communication with each other and the second and third bodies being in liquid communication with each other, the first body being relatively the coolest and the second body being hotter-than the third body, feeding oil field emulsion containing gas into the first body of liquid, reducing the head of said liquid substantially to zero in its passage from each body to the next, continuously withdrawing gas from the tops of the first and second bodies of liquid and withdrawing oil from the top and water from the bottom of the third body of liquid While maintaining said third body of liquid in a substantially quiescent state to effect stratification of oil and water by feeding liquid from said second body of liquid into a vertically intermediate point of said third body above the point of water drawoff therefrom and applying the bulk of the required heat to the emulsion in its passage from the first body to the second body to thereby makethis the hottest point in the path of travel of the emulsion. 6. An apparatus for handling an oil and water emulsion containing gas comprising a vessel divided into a plurality of compartments by upstanding partitions, all of said partitions terminating below the top of said vessel, said compartments including an inlet compartment, a gasseparation compartment and a settling compartment, the settling compartment being in liquid communication only with the gas separation compartment and a heating compartment disposed intermediate the inlet compartment and the gas separation compartment and'in liquid communication with both of said compartments. the walls of said heating compartment including at least one wall of each of said other compartments.

7. An apparatus for handling an oil and water emulsion containing gas comprising a vessel divided by partitions into a plurality of compart ments, said compartments including an inlet compartment, a gas separation compartment, a settling compartment and a transfer compartment between the gas separation compartment and the settling compartment, said transfer compartment being in liquid communication with the bottom of said settling compartment and arranged to receive liquid from said gas separation compartment by overflow from said gas separation compartment, a. heating compartment disposed intermediate the inlet compartment and the gas separation compartment, said heating compartment being arranged to receive liquid from the inlet compartment by the flow of the liquid over the partition defining said inlet compartment and being in liquid communication with said gas separation compartment, oil and water outlets arranged in the settling compartment and a gas outlet arranged on said vessel.

8. An apparatus for handling an oil and water emulsion containing gas comprising a vessel divided by upstanding partitions into a plurality of compartments, all of said partitions terminating below the top of said vessel, said compartments including an inlet compartment, a gas separation compartment, a settling compartment, and a transfer compartment between the gas separation compartment and the settling compartment, said transfer compartment being in liquid communication with the bottom of said settling compartment and arranged to receive liquid from said gas separation compartment by overflow from said gas separation compartment, a heating compartment disposed intermediate the inlet compartment and the gas separation compartment and in liquid communication with both of-said compartments, oil and water outlets arranged in the settling compartment, and a gas outlet arranged on said vessel.

9. A method for treating a gas-containing oilwater emulsion which comprises initially settling and withdrawing free water from the mixture, passing the remaining mixture through a heating zone, feeding the heated mixture into the lower portion of an upwardly flowing stream, spreading said mixture out into a thin layer at the upper end of said stream to thereby liberate the hot gas from the mixture, cascading the thin layer into a pool of constant level, withdrawing gas-free liquid from the lower portion of said pool into a quiescent settling zone in which oil and water are stratified and separately withdrawing oil and water from said zone.

10. An apparatus for treating an oil and water emulsion containing gas, comprising a vessel provided with upstanding partitions arranged to form an inlet compartment, including a water knock-out zone, having a bottom drawoff for. water and an upper outlet for residual emulsion containing gas, a gas separation zone and a settling zone with a common vapor space, a heating compartment at the lower end of said gas.

separation zone in liquid communication there with and arranged to receive residual emulsion containing gas from said inlet compartment, the flow of emulsion being from said inlet compartment through said heating compartment and upwardly through said gas separation zone, a weir provided at the upper end of said gas separation zone, over which liquid can overflow into said settling zone, separate water and oil outlets from said settling zone so arranged as to maintain the liquid level in said settling zone substantially below said weir, to thereby cause liquid to cascade from said gas separation zone into said settling zone, a bathe in said settling zone spaced from the bottom thereof to separate the portion thereof receiving the overflow from said gas separation zone from the remainder of said settling zone, and a gas outlet from said vapor space.

RUDOLPH C. BUCHAN. 

